• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.846-864
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• 2017

Software Defined Network (SDN) realizes management and control over the underlying forwarding device, along with acquisition and analysis of network topology and flow characters through south bridge protocol. Data path Identification (DPID) is the unique identity for managing the underlying device, so forged DPID can be used to attack the link of underlying forwarding devices, as well as carry out DoS over the upper-level controller. This paper proposes a dynamic defense method based on Client-Puzzle model, in which the controller achieves dynamic management over requests from forwarding devices through generating questions with multi-level difficulty. This method can rapidly reduce network load, and at the same time separate attack flow from legal flow, enabling the controller to provide continuous service for legal visit. We conduct experiments on open-source SDN controllers like Fluid and Ryu, the result of which verifies feasibility of this defense method. The experimental result also shows that when cost of controller and forwarding device increases by about 2%-5%, the cost of attacker's CPU increases by near 90%, which greatly raises the attack difficulty for attackers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2674-2697
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• 2019

Identity authentication is a crucial line of defense for network security, and passwords are still the mainstream of identity authentication. So far trawling password attacking has been extensively studied, but the research related with personal information is always sporadic. Probabilistic context-free grammar (PCFG) and Markov chain-based models perform greatly well in trawling guessing. In this paper we propose a systematic targeted attacking model based on structure partition and string reorganization by migrating the above two models to targeted attacking, denoted as TG-SPSR. In structure partition phase, besides dividing passwords to basic structure similar to PCFG, we additionally define a trajectory-based keyboard pattern in the basic grammar and introduce index bits to accurately characterize the position of special characters. Moreover, we also construct a BiLSTM recurrent neural network classifier to characterize the behavior of password reuse and modification after defining nine kinds of modification rules. Extensive experimental results indicate that in online attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 275%, and respectively outperforms its foremost counterparts, Personal-PCFG, TarGuess-I, by about 70% and 19%; In offline attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 90%, outperforms Personal-PCFG and TarGuess-I by 85% and 30%, respectively.

• 한국학교수학회논문집
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• 제1권1호
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• pp.151-163
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• 1998

In mathematics education, teaching-learning activity can be divided largely into the understanding the mathematical concepts, derivation of principles and laws, acquirement of the mathematical abilities. We utilize various media, teaching tools, audio-visual materials, manufacturing materials for understanding mathematical concepts. But sometimes we cannot define or explain correctly the concepts as well as the derivation of principles and laws by these materials. In order to solve the problem we can use the computer. In this paper, character and movement state of various quadratic function graph types can be used. Using the computers is more visible than other educational instruments like blackboards, O.H.Ps., etc. Then, students understand the mathematical concepts and the correct quadratic function graph correctly. Consquently more effective teaching-learning activity can be done. Usage of computers is the best method for improving the mathematical abilities because computers have functions of the immediate reaction, operation, reference and deduction. One of the important characters of mathematics is accuracy, so we use computers for improving mathematical abilities. This paper is about the program focused on the part of "the quadratic function graph", which exists in mathematical curriculum the middle school. When this program is used for students, it is expected the following educational effect. 1, Students will have positive thought by arousing interests of learning because this program is composed of pictures, animations with effectiveness of sound. 2. This program will cause students to form the mathematical concepts correctly. 3. By visualizing the process of drawing the quadratic function graph, students understand the quadratic function graph structually. 4. Through the feedback, the recognition ability of the trigonometric function can be improved. 5. It is possible to change the teacher-centered instruction into the student-centered instruction. For the purpose of increasing the efficiencies and qualities of mathmatics education, we have to seek the various learning-teaching methods. But considering that no computer can replace the teacher′s role, tearchers have to use the CIA program carefully.

• 대한수학교육학회지:수학교육학연구
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• 제22권2호
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• pp.229-259
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• 2012

본 연구는 우리나라 학생들의 수학적 신념을 간편하게 측정할 수 있는 표준화된 측정 도구를 문헌연구와 심리측정학적 분석을 바탕으로 수학교과에 대한 신념, 수학 문제해결 신념, 수학 교수 학습에 대한 신념, 수학적 자아개념의 4개의 하위 요소로 구성하여 중학생용은 총 37문항으로, 고등학생용은 총 40문항으로 개발하였다. 그리고 대단위 표집 검사를 실시하여 우리나라 중 고등학생의 수학적 신념이 학교급별, 성별, 성취수준에 따라 어떤 특성이 나타나는지를 분석하였다. 연구 결과, 중 고등학교 모두 남학생이 여학생보다 수학이 유용하다고 믿는 신념, 수학에서 과정보다 정답을 구하는 것이 중요하다고 믿는 신념, 많은 수의 문제를 푸는 것이 중요하고 믿는 신념 등이 강하게 나타났고, 중학교에서 고등학교로 진급하면서 수학적 자아개념 중 '감정' 요인이 긍정적으로 변화하였다. 여학생은 중 고등학교 모두 수학 교수 학습에 대한 신념 중 '교사의 수업활동' 요인만이 남학생보다 강하였다. 성취수준이 '기초이하' 집단 학생들이 수학은 암기해야 하는 공식과 절차라거나 창의적 활동에 대한 기회를 제공하지 못한다고 생각하는 '고정관념'이 가장 강하였다. 그 외요인에서는 '우수' 집단 학생들의 신념이 강하였다.

• 한국학교수학회논문집
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• 제23권2호
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• pp.179-201
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• 2020

본 연구는 한국과 미국의 기하 영역 교과서 과제에 제시된 실생활 맥락 과제를 수학적 모델링 관점에서 분석함으로써 두 나라 학생에게 주어진 수학적 모델링 학습기회의 다양성을 비교하는 것을 목표로 한다. 이를 위해, 각 나라 교과서 과제를 수학적 모델링 과정, 데이터, 표현종류의 세 가지 측면을 중심으로 분석하였다. 연구결과는 다음과 같다. 첫째, 수학적 모델링 과정과 관련하여, 한국 교과서의 경우 미국 교과서보다 수학적 모델링 과정의 모든 단계에서 더 높은 비중으로 과제를 제공한다. 둘째, 데이터의 특징과 관련하여, 두 나라 교과서 모두 적정 데이터 과제 비율이 가장 높으며, 한국의 경우 교과서별 데이터 특징의 격차가 크다. 셋째, 표현종류와 관련하여, 두 나라 교과서 모두 글과 그림 과제 비율이 가장 높다. 한국 교과서가 미국 교과서보다 교과서에 따른 표현종류의 차이가 크게 나타났으며, 일부 교과서의 경우 글과 그림을 제외한 다른 표현이 제시되지 않았다. 넷째, 세 가지 특징을 통합하여 과제를 분석한 결과, 세 가지 측면이 다양하게 다루어지기보다 적정 데이터를 글과 그림으로 제시한 뒤 수학 결과를 얻는 데 초점을 둔 과제가 주로 제시되었다. 한국 교과서와 달리 미국 교과서에만 제시된 과제로, 과잉 데이터가 글로 제시되어 수학화를 요구하는 과제가 확인되었다.

• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.1057-1064
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• 2007

From the view of natural language process, quantitative linguistic analysis is a linguistic study relying on statistical methods, and is a mathematical linguistics in an attempt to discover various linguistic characters by interpreting linguistic facts quantitatively through statistical methods. In this study, I would like to introduce a quantitative linguistic analysis method utilizing a computer and statistical methods on literary works. I also try to introduce a use of SynKDP, a synthesized Korean data process, and show the relations between distribution of linguistic unit elements which are used by the hero in a novel #Sassinamjunggi# and theme analysis on literary works.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제25권1호
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• pp.185-205
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• 2011

본 연구는 전남대학교 과학영재교육원 중등수학 사사과정에 있는 수학영재 학생을 대상으로 사사독립연구를 실시하여 수확영재의 사사독립연구에서 얻어진 산출물에서 나타난 특징을 분석하고, 산출물 발표과정에서의 영재학생의 심리적 변화에 대하여 연구하였다. 연구 결과 다음과 같은 결론을 얻었다. 첫째, 영재학생의 사사독립연구는 수학영재성 중 수학적 능력의 구성요소만 귀납적 연역적 추론 능력을 발현하게 한다. 둘째, 영재학생의 사사독립연구에 대한 산출물 발표는 영재학생에게 수학영재성 관련된 창의적인 문제해결 능력 중 수학적 능력인 의사소통능력이 영재학생에게서 발현하게 한다. 셋째, 영재학생의 사사독립연구에 대한 산출물 발표는 영재학생에게 수학 영재성의 구성요소 중 자신의 능력에 대한 믿음, 자기 신뢰감 등과 관련된 요소를 상승하게 한다.

• 한국학교수학회논문집
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• 제2권1호
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• pp.55-66
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• 1999

In mathematics education, teaching-learning activity can be divided largely into the understanding the mathematical concepts, derivation of principles and laws acquirement of the mathematical abilities. We utilize various media, teaching tools, audio-visual materials, manufacturing materials for understanding mathematical concepts. But sometimes we cannot define or explain correctly the concepts as well as the derivation of principles and laws by these materials. In order to solve the problem we can use the computer. In this paper, ′the process of the length of curve being equal to the sum of the vectors when intervals get smaller′ and ′the process of calculating volume of spinning curve by using definite integral.′ Using the computers is more visible than other educational instruments like blackboards, O.H.Ps., etc. Also it can help students with solving mathematical problems intuitively. Consequently more effective teaching-learning activity can be done. Usage of computers is the best method for improving the mathematical abilities because computers have functions of the immediate reaction, operation, reference and deduction. One of the important characters of mathematics is accuracy, so we use computers for improving mathematical abilities. This paper is about the program focused on the part of "the application of definite integral", which exists in mathematical curriculum the second and third grade of high school. When this study is used for students as assisting materials, it is expected the following educational effect. 1. Students will have precise concepts because they can understand what they learn intuitively. 2. Students will have positive thought by arousing interests of learning because this program is composed of pictures, animations with effectiveness of sound. 3. It is possible to change the teacher-centered instruction into the student-centered instruction. 4. Students will understand the relation between velocity and distance correctly because they can see the process of getting the length of curve by vector through the monitor. For the purpose of increasing the efficiencies and qualities of mathematics education, we have to seek the various learning-teaching methods. But considering that no computer can replace the teacher′s role, teachers have to use the CIA program carefully.

• 대한수학회지
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• 제34권4호
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• pp.871-894
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• 1997

For a lifted nontrivial additive character $\lambda'$ and a multiplicative character $\chi$ of the finite field with $q^2$ elements, the 'Gauss' sums $\Sigma\lambda'$(tr $\omega$) over $\omega$ $\in$ SU(2n + 1, $q^2$) and $\Sigma\chi$(det $\omega$)$\lambda'$(tr $\omega$) over $\omega$ $\in$ U(2n + 1, $q^2$) are considered. We show that the first sum is a polynomial in q with coefficients involving certain new exponential sums and that the second one is a polynomial in q with coefficients involving powers of the usual twisted Kloosterman sums and the average (over all multiplicative characters of order dividing q-1) of the usual Gauss sums. As a consequence we can determine certain 'generalized Kloosterman sum over nonsingular Hermitian matrices' which were previously determined by J. H. Hodges only in the case that one of the two arguments is zero.

• 대한수학회지
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• 제46권4호
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• pp.733-746
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• 2009

For any integer k $\geq$ 2, let P(c, k + 1;q) be the number of all k+1-tuples with positive integer coordinates ($a_1,a_2,...,a_{k+1}$) such that $1{\leq}a_i{\leq}q$, ($a_i,q$) = 1, $a_1a_2...a_{k+1}{\equiv}$ c (mod q) and 2 $\nmid$ ($a_1+a_2+...+a_{k+1}$), and E(c, k+1; q) = P(c, k+1;q) - $\frac{{\phi}^k(q)}{2}$. The main purpose of this paper is using the properties of Gauss sums, primitive characters and the mean value theorems of Dirichlet L-functions to study the hybrid mean value of the r-th hyper-Kloosterman sums Kl(h,k+1,r;q) and E(c,k+1;q), and give an interesting mean value formula.